European pharmaceutical giant Roche has extended its $4.8 billion offer for Spark Therapeutics to May 2 after failing to secure all of its shares, the former said in a press release on Wednesday.

Roche previously submitted a tender offer to purchase all outstanding shares of Spark’s common stock at the end of February. Spark then had to recommend to its shareholders that they tender their shares to Roche after which the latter would acquire the shares at $114.50 apiece. However, as Roche had acquired only 29.4% of Spark's shares by Wednesday and the offer was due to expire by the end of the day, the offer was extended until May 2. All of its other terms and conditions would remain unchanged during the extension period, Roche said.

The news comes after rival Novartis recently acquired IFM Tre from Bristol-Myers Squibb Co. for an undisclosed sum. The Swiss pharmaceutical giant provided few details of the transaction but highlighted one clinical and two preclinical programs targeting the NLRP3 inflammasome complex with selective inhibition.